// 定义类型别名
type StrType = string | number | boolean;

let str1: StrType = false;
let str2: StrType = 123;
let str3: StrType = "12456";

function fun(a: string, b: number, c: number): number {
  return a.length + b + c;
}

type Funtype = (a: string, b: number, c: number) => number;

let fun3:Funtype = (a,b,c)=>{
    return a.length +b +c
}

fun3('13233',12,12)